As a power circuit, there is known, for example, a DC-to-DC converter that converts a DC (direct current) voltage. For example, in an information processing device such as a server or a home appliance, an AC voltage is converted to a DC voltage using a rectifier and a power factor correcting circuit. Then, the DC voltage is stepped down using a DC-to-DC converter.
As such a DC-to-DC converter, there is known a multiphase switching power circuit in which a plurality of switching circuits having different phases is connected in parallel between an input terminal and an output terminal.
In a switching power circuit, a switching frequency may vary depending on the size of a load in order to improve efficiency. In a multiphase switching power supply, however, when the switching frequency is changed to improve the efficiency of the power circuit, the timings of frequency conversion may be misaligned due to the plurality of switching circuits. As a result, the frequencies may not be switched properly.
The following are reference documents.
[Document 1] Japanese Laid-Open Patent Publication No. 2004-056838 and
[Document 2] Japanese Laid-Open Patent Publication No. 2006-340442.